There's a shortage of COBOL developers that are needed to maintain and update legacy financial mainframes that still don't make economic sense to replace since they operate at critical infrastructure points 24/7 and over the years have become pretty bulletproof.

Replacing these systems is extremely difficult since they're so relied on a replacement needs to be nearly flawless form the start. If you stumble upon on a bug in your international wire transfer code you could be messing up a $10 billion international aid wire that was meant for hundreds of factories.